Optical turbulence measurement and acoustic sounder calibration using hot-wire anemometers

Abstract

Optical turbulence conditions at a mountain peak (North Oscura Peak, NM) have been calculated using two hot-wire anemometers. The anemometers (running in constant current mode, with a very low overheat ratio) measure temperature fluctuations. Combining the fluctuating temperature data with wind velocity data, local temperature and pressure, and invoking Taylor's hypothesis, the optical turbulence parameters can be calculated. These parameters include temperature structure parameter (C 2 t ) and the refractive index structure parameter (C 2 n ). The two probes are positioned at different elevations above the ground, thus the vertical optical turbulence gradient can be calculated. This relationship is used to calibrate an acoustic sounder. Optical turbulence data collected from the hot-wire anemometers as well as the acoustic sounder will be compared to meteorological events measured locally. Many days of data have bene collected and will be shown, of particular interest is the relationship between optical turbulence and solar radiation, as well as wind speed and direction. The diurnal relationship of the optical turbulence gradient will also be shown. As well as the effect of this parameter on the acoustic sounder calibration.